Alkynyl gold(I) phosphane complexes: evaluation of structure-activity-relationships for the phosphane ligands, effects on key signaling proteins and preliminary in-vivo studies with a nanoformulated complex

Abstract

The synthesis and characterization of four organometallic gold(I) complexes containing different water soluble phosphanes (TPPTS, PTA and DAPTA) and chromophoric units (4-pyridylethynyl and propargyloxycoumarin) is here reported. The analysis of their absorption and emission spectra led us to attribute their luminescent behaviour to the chromophoric organic ligands. Moreover, the presence of the gold(I) metal atom has been observed to be the responsible of an efficient intersystem crossing process responsible for the observed phosphorescence emission. Broad emission bands are observed in most cases due to the formation of organized aggregates in solution in agreement with microscopic characterization. Biological activity of the complexes showed very low effects against tumor cell growth but an inhibitory potency against thioredoxin reductase (TrxR). The missing / low cytotoxic effects could be related to a low bioavailability as determined by atomic absorption spectroscopy.